Die set with two-part leader pins

ABSTRACT

Disclosed herein is a die set in which the punch holder is guided for reciprocating movement towards and away from the die shoe by two-part leader pins, with the upper leader pin portions fixed to the punch holder and the lower leader pin portions fixed to the die shoe. Tapered surfaces on the upper leader pin portions are received in tapered sleeves on the lower leader pin portions to guide the movement of the punch holder. The tight fit of the tapered surfaces minimizes deflection of the punch holder to provide more accurate punching. Provision is also made for selecting the depth of stroke of the punch holder, and thus the punch, by utilizing a boss or stop on the end of the upper leader pin portion, which stop engages an abutment on the lower leader pin portion. The boss can be ground to the selected length to provide the desired travel of the punch holder and punch with respect to the work material and female die portion.

United States Patent Janiszewski 5] Dec. 16, 1975 DIE SET WITH TWO-PARTLEADER PINS [57] ABSTRACT [76] Inventor: Kasimlr janlszewski 8 Disclosedherein is a die set in which the punch holder Loomls Road Franklm 53132is guided for reciprocating movement towards and [22] Fil d; S 20, 1974away from the die shoe by two-part leader pins, with the upper leaderpin portions fixed to the punch [21] Appl' 5073637 holder and the lowerleader pin portions fixed to the die shoe. Tapered surfaces on the upperleader pin 52 us. Cl. 83/637; 308/4 0 Portions are reeeived in teperedSleeves Oh the lower [51] Int. cl. B26D 5/20; F16C 29/02 leader Pportions to guide the movement Of the [58] Field of Search 83/637, 635,698, 638; Puheh heldee The tight fit 0f the tapered Surfaces 303/4 Cminimizes deflection of the punch holder to provide more accuratepunching. Provision is also made for [56] References Ci selecting thedepth of stroke of the punch holder, and UNITED STATES PATENTS thus thepunch, by utilizing a boss or stop on the end 9 9 of the upper leaderpin portion, which stop engages an 3,321,222) 2; jantszeast abutment onthe lower leader pin portion. The boss 3279870 10/1966 zxzzz z z 308/4 Ccan be ground to the selected length to provide the desired travel ofthe punch holder and punch with rey E w u Abercrombie spect to the Workmaterial and female portion. Attorney, Agent, or FzrmHenry C. Fuller 9Claims, 4 Drawing Figures l Z? i US. Patent Dec.16,1975 Sheet10f23,926,083

US. Patent Dec. 16,1975 Sheet20f2 3,926,083

DIE SET WITH TWO-PART LEADER PINS SUMMARY OF THE INVENTION The inventionprovides a die set which employs twopart leader pins for guidingreciprocal movement of the punch holder with respect to the die shoe andfor controlling the length of travel of the punch holder towards the dieshoe. Tapered male and female surfaces on adjacent ends of the two-partleader pins provide for a precise positioning of the male die or punchwith respect to the female die with minimal deflection when the workmaterial is engaged. The tapered surfaces are adjusted so that they arein shear when the punch is engaged with the work material so that thereis no lateral deflection or translatory displacement of the punch formore accurate work than with a conventional die set.

Means are provided for adjusting the fit of'the tapered surfaces and foradjusting the depth of penetration for precise control of the punch.This is particularly desirable when punching thin stock such as with alamination die for transformer plates. With the die set of the inventionthe punch can be controlled so that the punch does not enter the femaledie, which results in a longer life for the punch.

Further objects, advantages and features of the invention will becomeapparent from the following disclosure.

DESCRIPTION OF THE DRAWINGS DETAILED DESCRIPTION Although the disclosurehereof is detailed and exact to enable those skilled in the art topractice the invention, the physical embodiments herein disclosed merelyexemplify the invention which may be embodied in other structure. Thescope of the invention is defined in the claims appended hereto.

The die set conventionally includes a punch holder connected to amounting lug 12, and a die shoe 14. The punch holder 10 carries a punchor male die member 16, and a female die 18 is supported on the die shoe14. In accordance with the invention there are provided upper leader pinportions 20 which can have a tapered shank 22 and be in a press fit inapertures 24 in the punch holder 10. The leader pin portions 20 are alsoprovided with a tapered surface 26 which can be a continuation oftapered surface 22.

The leader pins 20 can also include an adjustment boss or stop 28 whichprojects axially form the lower surface 30 of the tapered portion 26.The purpose of the adjustment boss 28 will be hereinafter described indetail.

The lower leader pin portions 32 can have tapered surfaces 34 receivedin tapered apertures 36 in the die shoe. Projecting above the die shoeis a lower leader pin shank portion 38. Shank portion 38 is connected toa sleeve 40 which is provided with an internal tapered surface 42complementary to the tapered surface 26. Means are providedforadjustably securing the sleeve 40 to the lower leader pin portion 32.In the construction disclosed in FIG. 1, the means comprises set screws44. The set screws 44 enable adjustment of the position of the sleeve 40relative to the die 18 or material to be punched 39 so that the taperedsurfaces are in tight engagment or in shear at a point duringpenetration of the work material which enables separation of the punchedblank from the work material 39 with no deflection of the punch.

In use of the die set thus described, the adjustment boss or stop 28constitutes an adjustable stop which limits downward movement of thepunch as it engages the top 41 of the lower leader pin portion 38. Theuser of the die set can thus grind the stop 28 to the desired depth tocontrol travel of the punch and the depth of penetration of the punchinto the female die 18. The adjustment of sleeve. 40 is also taken intoconsideration when adjusting the stop 28. Although a stop 28 is shown inFIG. 1, if the die set and thus the leader pins are quite small, thestop28 can be eliminated and the surface 30 of the upper leader pin portioncan be ground to the correct length. The surface 30 and sur face 41 willlimit travel of the punch holder to the selected distance. g

FIG. 3 shows a modified embodiment of the invention in which the upperleader pin portion 50 is provided with a threaded bore 52 which receivesa set screw 54 which is adjusted to set the travel of the punch holderand punch.

FIG. 4 shows a further embodiment in which the upper leader pin portion60 is provided with circumferential oil grooves 62 intersected byaxially-extending oil grooves 64. The adjacent ends 66, 68 of the upperand lower leader pins can be provided with bores 70, 72 toserve as oilreservoirs for lubricating oil 78. The reciprocating movement of theupper leader pin portion 60 in sleeve 76 provides a pumping action toforce oil between the ends 66 and 68 into the grooves 62, 64. Thelubricating arrangement as thus described considerably lengthens theintervals for oil replacement which minimizes scoring and wearingproblems which exist with conventional die sets.

As shown in FIG. 1, the mounting lug 12 for the punch holder isdesirably provided with a tapered shank portion 80 which fits in atapered opening 82 in the punch holder. The lug 12 is thus securedagainst withdrawal or severance from the punch holder 10 during upwardmovement of the punch holder 10.

The upper and lower leader pin portions are also provided with taperedsurfaces to prevent withdrawal. The tapered surfaces 22 and 36 on theleader pins prevent separation of the leader pins from the punch holderand die shoe during use. The ram prevents withdrawal of the pin portions20 from the punch holder during downward movement of the punch holderand the bolster plate 84 prevents withdrawal of the lower pin portions32.

The tapered surfaces 26, 42 of the upper leader pin portion 20 and thesleeve 40 desirably have a taper of about 0.003 inches per inch althoughthe taper is more pronounced in the drawings.

The use of two-part leader pins with tapered guiding surfaces andabutting ends enables control of the punch so that no penetrationbf thefemale die occurs. Thus wear of the male and fhi'ale die is reduced to aminimum. ln the event wear of the punch does occur and the punch isground, the boss 28 or the end of the upper leader pin portion is alsoground to maintain the travel of the punch at the selected distance.

What is claimed is:

1. ln a die set including a punch holder and a die shoe, the improvementcomprising an upper leader pin portion mounted on said punch holder andhaving a tapered surface decreasing in diameter remote from said punchholder, a lower leader pin portion anchored in said die shoe and havinga tapered bore complementary to said tapered surface of said leader pinand adapted to telescopically and reciprocally receive said upper leaderpin tapered portion and guide said punch holder during reciprocalmovement of said punch holder and leader pin toward and away from saiddie shoe.

2. In a die set including a punch holder and a die shoe, the improvementcomprising an upper leader pin portion mounted on said punch holder andhaving a tapered surface decreasing in diameter remote from said punchholder, a lower leader pin portion connected to said die shoe and havinga tapered bore adapted to receive said upper leader pin tapered portionand guide said punch holder during reciprocal movement of said punchholder toward and away from said die shoe and wherein said bore isformed by a sleeve separable from said lower leader pin portion, andsaid sleeve has a bore for receiving said upper pin portion, and meansfor adjustably connecting said sleeve on said lower pin portion.

3. In a die set including a punch holder and a die shoe, the improvementcomprising an upper leader pin portion mounted on said punch holder andhaving a tapered surface decreasing in diameter remote from said punchholder, a lower leader pin portion connected to said die shoe and havinga tapered bore adapted to receive said upper leader pin tapered portionand guide said punch holder during reciprocal movement of said 4 punchholder toward and away from said die shoe and wherein said upper leaderpin portion has an adjustable stop and wherein said lower leader pinportion has an abutment portion engageable with said stop to limittravel of said punch holder.

4. The improvement of claim 3 wherein said stop comprises a projectingboss extending axially of said upper leader pin portion, the boss havinga diameter less than said leader pin.

5. The improvement of claim 2 wherein said tapered surfaces of saidupper and lower leader pin portions have a slope such that said surfacesmate at a preselected point in the travel of the punch to preventdeflection of the punch.

6. The improvement of claim 2 wherein said upper leader pin portion hasintersecting axially and circumferentially extending oil grooves andincluding an oil reservoir in said lower leader pin portion.

7. The improvement of claim 3 wherein said adjustable stop comprises athreaded bore in said upper leader pin portion and a screw threadablyreceived in said bore and adapted to engage said lower leader pinportion.

8. A die set in accordance with claim 2 wherein said punch holder has atapered opening for receiving tapered surfaces on said upper leader pinportions with the tapered openings increasing in diameter toward thepunch holder surface remote from the die shoe.

9. A die set having a punch holder and die shoe, the improvementcomprising a mounting lug on said punch holder connectable with a ram,said mounting lug including a tapered shank portion and an aperture insaid punch holder having a tapered surface for receiving said taperedlug surface, said aperture having its largest diameter at the punchholder surface adjacent the die

1. In a die set including a punch holder and a die shoe, the improvementcomprising an upper leader pin portion mounted on said punch holder andhaving a tapered surface decreasing in diameter remote from said punchholder, a lower leader pin portion anchored in said die shoe and havinga tapered bore complementary to said tapered surface of said leader pinand adapted to telescopically and reciprocally receive said upper leaderpin tapered portion and guide said punch holder during reciprocalmovement of said punch holder and leader pin toward and away from saiddie shoe.
 2. In a die set including a punch holder and a die shoe, theimprovement comprising an upper leader pin portion mounted on said punchholder and having a tapered surface decreasing in diameter remote fromsaid punch holder, a lower leader pin portion connected to said die shoeand having a tapered bore adapted to receive said upper leader pintapered portion and guide said punch holder during reciprocal movementof said punch holder toward and away from said die shoe and wherein saidbore is formed by a sleeve separable from said lower leader pin portion,and said sleeve has a bore for receiving said upper pin portion, andmeans for adjustably connecting said sleeve on said lower pin portion.3. In a die set including a punch holder and a die shoe, the improvementcomprising an upper leader pin portion mounted on said punch holder andhaving a tapered surface decreasing in diameter remote from said punchholder, a lower leader pin portion connected to said die shoe and havinga tapered bore adapted to receive said upper leader pin tapered portionand guide said punch holder during reciprocal movement of said punchholder toward and away from said die shoe and wherein said upper leaderpin portion has an adjustable stop and wherein said lower leader pinportion has an abutment portion engageable with said stop to limittravel of said punch holder.
 4. The improvement of claim 3 wherein saidstop comprises a projecting boss extending axially of said upper leaderpin portion, the boss having a diameter less than said leader pin. 5.The improvement of claim 2 wherein said tapered surfaces of said upperand lower leader pin portions have a slope such that said surfaces mateat a pre-selected point in the travel of the punch to prevent deflectionof the punch.
 6. The improvement of claim 2 wherein said upper leaderpin portion has intersecting axially and circumferentially extending oilgrooves and including an oil reservoir in said lower leader pin portion.7. The improvement of claim 3 wherein said adjustable stop comprises athreaded bore in said upper leader pin portion and a screw threadablyreceived in said bore and adapted to engage said lower leader pinportion.
 8. A die set in accordance with claim 2 wherein said punchholder has a tapered opening for receiving tapered surfaces on saidupper leader pin portions with the tapered openings increasing indiameter toward the punch holder surface remote from the die shoe.
 9. Adie set having a punch holder and die shoe, the improvement comprising amounting lug on said punch holder connectable with a ram, said mountinglug including a tapered shank portion and an aperture in said punchholder having a tapered surface for receiving said tapered lug surface,said aperture having its largest diameter at the punch holder surfaceadjacent the die shoe.